Cathode for electrolytic condensers



Oct. 4, 1932. J. E. u |ENFE| D CATHODE FOR ELECTROLYTIC CONDBNSERS Filed June 19. 1930 ArTo'RNEY Patented Oct. 4,` 1932 UNITED STATES PATENT oFFIcE CATHODE FOB ELECTBOLYTIC CONDENSEBS -Application med June 19, 1930. 'Serial 110.162.254.

The inventionV relates to electrical condensers of the electrolytic type, and to a novel method of operating the same. l In the operation of electrolytic condensers, it has been found desirable in many cases to constitute the cathode of the condenser of the same metal as that of which the anode iscom= posed for the purpose of reventing contamination of the electrolyte y the introduction of large amounts of 'forelgn matter. Disturbances in the operation, however, have resulted especially when aluminum has been utilized as the particular metal. For example, it has been found that the impedance of a condenser would increase if operated on A. C. voltages; and if the condenser be utilized in D. C. circuits, as for filtering purposes, the eiiiciency would drop appreciahly. In explanation of these phenomena, the View has been advanced that an aluminum cathode will lm, even at a high negative potential, if an A. C. component-pulsating voltage or ri ple-is present in the circuit. This conce tion led to rather ex ensive expedients w ere a metal container or the electrolyte was intended for use as the cathode. For example, such containers were made of pure copper; or, the cathode would be constitutedyof a lar e area of aluminum allo possessin enoug foreign additions to obviate the`fiming action under the low current densities.. 1

v I have found that the physical reason for the ditliculty indicated above' has nothing in .common with the pulsations of the voltage at the cathode, the correct explanation being that the potential of the electrolyte, which is always negative with resect to the anode, may lincidentallydrop suA ciently to become slightly negative .with respect to the cathode.

When the cathode i's then of a filming material, this will result in the formation of a film thereon.which,in`turn, will cause the. potential ofthe electrolyte to become more negative. This will continueA and the potential distribution will be in unstable equilibrium until the cathode is covered by the ultimate amount of film,

It is the object of the present invention to obviate such action; and in operating the novel condenser the electrolyte and cathodic electrode of such condenserare maintained at i equi-potential by discharging from said electrolyte to the cathodic electrode charges developing potentials negative thereto. This may conveniently be\ effected by extending into the electrolyte from the cathodic electrode a sounder member of a non-filming metal, which sounder short-circuits the electrolyte, therefore, to the said electrode so that the former will never be permitted to become negative with respect to the latter. The area of this sounder member-ma extremely'small relatively to the area o the Catlmdic` electrode in view of the small charges which it' has to accommodate. Its presence, moreover, will enable the entire area of the said electrode to remain active.

The nature of the invention, however, will best be understood when described in connection with the accompanying drawing, which is a vertical section through the novel condenser.

As indicated, the condenser comprises la container, in the present instance constituted by the cathode 1 which, for example, may be set forth in my co-pending application, Serialv N o. 462,250 for Electrolytic Condenser led of even date herewith.

`^ The anode 3 of the condenser is then also of aluminum and is provided with the ter -as is also set forth in the aforesaid co-pendas the former.

This may be effected in a simple manner merely by introducing a metallic sounder member which projects into the electrolyte from the said cathode 1 so that the latter may a sounder of a non-filmin denser, an

impart a charge by means of said sounder to the said electrolyte for preventing the electrolyte becoming more negative than the said cathode. I have found that by securing a copper rivet6, of negligible size relatively to the cathode, through the Wall of the said cathode l, this effect may readily be accomplished as the inner head of the rivet will be in direct Contact with the electrolyte while at least its shankand outer head are in contact with the cathode.

I claim:

1. In an electrolytic condenser comprising a metallic container for electrolyte and an l anodic electrode therein, the container bein of the same metal as the anodic electrode an constituting the cathodic electrode therefor:

metal short-circuiting the electrolyte to t e cathodic electrode.

2. In an electrolytic condenser comprising a metallic container for electrolyte and an anodic electrode therein,the container bein of the same metal as the anodic electrode an y constituting the cathodic electrode therefor: a sounder of a non-filming metal short-circuting the electrolyte to the cathodic electrod'e-and of' area relativel small with respect to that of said cathodlc electrode.

3. In an electrolytic condenser comprising an aluminum container for elctrolyte and constitutin the cathodic electrode of the conan aluminum anodicelectrode therein: 'a sounder of a non-filming metal projecting therein from the container and short-circuiting the electrolyte to said container.

4. In an electrolytic condenser comprisingl an aluminum container for clctrolytel and constituting the cathodic electrode of the condenser, and an aluminum anodic electrode therein a sounder of copper projectin therein from the container and short-circuitlng the electrolyte to said container.

5. In an electrolytic condenser comprisin I an aluminum container for electrolyte an v constitutin the cathodic electrode of the condenser, an an aluminum anodic electrode therein: a rivet of a non-Elming metal pass- 

